There is a growing need for structures that provide personal protection against toxic chemical and biological agents. It is known to devise structures that are impermeable to toxic chemical vapors and liquids, but, when used as apparel, such structures are typically also hot, heavy and uncomfortable to wear.
The degree of comfort offered by apparel worn as a protective suit is significantly affected by the amount of water vapor that can permeate through the fabric from which the suit is made. The human body continuously perspires water as a method for controlling body temperature. When a protective fabric hinders the loss of water vapor from the body, the transpirational cooling process is hindered, which leads to personal discomfort. When a protective suit allows little or no loss of water vapor, extreme heat stress or heat stroke can result in a short period of time. Hence, it is desirable that, in addition to offering the highest levels of protection against toxic chemicals and liquids, a practical chemical and biological protective suit should have high water vapor transmission rates. It is also desirable that the appropriate protective structure be light in weight and offer the same high level of protection over a long period of time.
U.S. Pat. No. 5,362,717 discloses methods for preparing N-halochitosans, including N-chlorochitosan, N-bromochitosan, and N-iodochitosan. The N-halochitosans are used to induce flocculation of materials such as proteins, algae, carbohydrates, oils (edible and hydrocarbon), metallic oxides, poultry processing waste water and brewery sludge. The N-halochitosans were obtained and used as solids isolated by filtration or created in situ by adding a chitosan solution to the dispersion to be flocculated, then adding a halogenating agent.
The present disclosure provides selectively permeable laminates that contain N-halochitosan in the form of a continuous film or a powder and that can be used in articles for personal protection, providing improved wearer comfort compared with impermeable articles.